CHICAGOZoledronic acid (Zometa) significantly decreased skeletal
complications and bone pain in men with hormone-refractory prostate cancer and
bone metastases, compared with placebo, according to an update of a phase III
study presented at the 2003 Annual Meeting of the American Urological
Association (abstracts 1472 and 1473).
After 24 months of follow-up, the percentage of men who had at least one
skeletal-related event was 49% in the placebo group vs 38% in the treatment
group, a relative reduction of 22% and an absolute reduction of 11%, reported
Fred Saad, MD, associate professor of urology and director of urology oncology,
Montreal Cancer Center, University of Montreal.
Among men treated with zoledronic acid, there was a 5-month delay in the
median time to the first skeletal-related event and a 6.5-month delay in the
time to the first pathologic fracture, compared with placebo.
"Probably the most important endpoint was the multiple event analysis that
took into consideration the proportion of patients having skeletal-related
events, the time between events, and the number of events that occurred per
patient," Dr. Saad said. In the multiple events analysis, the risk of
developing a skeletal complication was 36% lower for patients treated with the
bisphosphonate (P = .002).
Differences in pain scores between zoledronic acid and placebo were
statistically significant at 3, 9, 21, and 24 months. Men treated with
zoledronic acid also had significantly less need for radiation treatments
directed to bone, which suggests that the bisphosphonate provides improved pain
control, Dr. Saad said.
"There were few adverse events that were unexpected, and renal toxicities
were limited and identical to placebo at the 4-mg zoledronic acid dose. So we
feel this is a new treatment option for patients with metastatic prostate
cancer," he said.
When asked his opinion about the possible use of zoledronic acid earlier in
the prostate cancer disease process, Dr. Saad said, "My gut feeling is that it
will have a benefit, but we need a study to prove it. That is the next logical
step, and a study is going to be started very shortly on that topic."